Jennifer Konikowski

What is the most important thing in your life? If you say Slack emojis, then you maybe have a misplaced sense of importance, but also, I understand. One of my current slacks has over 4,000 emojis. I wanted to pull them all down so I could add the ones that aren’t inside jokes to another slack… but how? There are a number of JS scripts out there that say that they will do this but I think Slack has since updated the JSON that they send so those didn’t work anymore. Being a rubyist, I wrote a parser for that JSON to export all the emojis. Downside: I still had to download all the JSON files. If you are more ambitious than me, I’m sure there is a way to do that via JavaScript fairly easily.

Go to https://your-slack.slack.com/customize/emoji
Open up developer tools then the network tab.
Filter by XHR or just search for emoji.adminList (might have to reload the page).

4. Copy and paste into a file called emoji#{number}.json with #{number} being the file number.

5. Keep scrolling down and keep copying and pasting and creating files.

6. Download the script into the same directory

7. Run script like this: ruby download_emojis.rb NUMBER_OF_FILES_CREATED Note: NUMBER_OF_FILES_CREATED should be replaced with however many files you created. It defaults to 10.

8. The files will be created in an emojis folder with the name of the emoji as the file name.

Why would you need to do this? Let’s say you have three production nodes: server1.test.com, server2.test.com, server3.test.com. In general, your production application (at prod.test.com) point to server1.test.com. But OH NO you totally messed something up on that node and you need to easily failover to server2.test.com. Easiest way? If they all have matching server host keys, you can just point prod.test.com to server2’s ip and you won’t get any errors. Otherwise, you’ll get loads. I also added a noop (no operation) mode to this script so it could be run as ./move_keys.sh -n and only print out the lines that it would run.

This script is written to be run on the server you want to copy the keys from as your user, which means you have to have ssh access into each server. For each server in the list that is not the host, it backs up the /etc/ssh directory, rsyncs the keys over, restarts ssh, then removes the relevant lines for that server in the known_hosts file.

#!/bin/bash
# use noop mode by passing -n
NOOP=false
# parse the options
while getopts 'n' opt ; do
  case $opt in
    n) NOOP=true ;;
  esac
done

SSHC='/usr/bin/ssh'
HOST=`hostname -f`

# Params: $1, host to log into and copy ssh dir into backup dir
copyit() {
  if [ $NOOP = true ]
  then
    echo "$SSHC -A $1 'sudo cp -r /etc/ssh /etc/ssh_bak_$(date +%Y%m%d%H%M)'"
  else
    $SSHC -A "$1" "sudo cp -r /etc/ssh /etc/ssh_bak_$(date +%Y%m%d%H%M)"
  fi
}

# Params: $1: src path, $2: dest path
moveit () {
  if [ $NOOP = true ]
  then
    echo "sudo -E rsync -avz -e 'ssh -o StrictHostKeyChecking=no' --rsync-path='sudo rsync' $1 $2"
  else
    sudo -E rsync -avz -e 'ssh -o StrictHostKeyChecking=no' --rsync-path='sudo rsync' $1 $2
  fi
}

# Params: $1, host to log into
restartit() {
  if [ $NOOP = true ]
  then
    echo "$SSHC -A $1 'sudo service ssh restart'"
  else
    $SSHC -A "$1" "sudo service ssh restart"
  fi
}

# Parmas: $1: host to deploy keys to
removeknown() {
  if [ $NOOP = true ]
  then
    echo "sudo ssh-keygen -f '/root/.ssh/known_hosts' -R $1"
    echo ""
  else
    sudo ssh-keygen -f "/root/.ssh/known_hosts" -R $1
  fi
}

# Params: $1: host to deploy keys to
movekeys () {
  copyit "$1"
  moveit "/etc/ssh/ssh_host_key" "$USER@$1:/etc/ssh/"
  moveit "/etc/ssh/ssh_host_key.pub" "$USER@$1:/etc/ssh/"
  restartit  "$USER@$1"
  removeknown "$1"
}


set -e

declare -a Servers
Servers[0]='server1.test.com'
Servers[1]='server2.test.com'
Servers[2]='server3.test.com'

Servers_minus_host=( ${Servers[@]/$HOST*/} )

for server in "${Servers_minus_host[@]}"
do
  movekeys $server
done

Important Code: Exporting Slack Emojis

A Bash Script For When You Need To Duplicate Host Keys Across Servers